I am in the process now of attempting the transfer again. I did not delete the old .img from the card, and assumed that might be the problem. The only thing left on the card when I started this time was GPX files. As far as other maps covering that area, they overlying maps are there, and I can see them, but City Nav does not even show up as a show/hide map option in the menu. I generally run with all maps but city Nav turned off, and only when I am fishing/hiking/walking/screwing around do I turn off city nav and turn on the appropriate map.